1. Field of the Invention
The present invention relates to an organic light emitting display, and a method of manufacturing the same.
2. Description of the Related Art
An image display for displaying various types of information on a screen corresponds to a core technology in the age of information communication and is developing in the direction toward a thinner, lighter, portable, and higher-performance display. Accordingly, an organic light emitting display for displaying an image by controlling the quantity of light emitted from an organic light-emitting layer is in the spotlight as a flat display device capable of reducing the weight and the volume of the display, which correspond to shortcomings of a Cathode Ray Tube (CRT).
The organic light emitting display is a self-emission device using a thin light-emitting layer between electrodes and has an advantage in that it can be thinned like paper.
A typical organic light emitting display has a structure including a sub-pixel driving unit array and an organic light emitting any formed on a substrate, wherein a light emitted from organic light emitting devices of the organic light emitting array displays an image while passing through the substrate of a barrier layer.
An organic light emitting device is susceptible to both degradations by internal factors, such as degradation of an electrode and a light-emitting layer by oxygen and degradation by reaction between a light-emitting layer and interface, and degradations by external factors, such as external moisture, oxygen, ultraviolet rays, and manufacturing conditions. Especially, since the external oxygen and moisture have a fatal influence on the lifespan of the device, packaging of the organic light emitting display is very important.
As a method for the packaging, a method of sealing a substrate having organic light emitting devices formed thereon by a protective cap is used. In this method, a moisture absorbent is attached to an inner central portion of the protective cap before the protective cap is sealed, to absorb moisture that may exist in the protective cap.
Further, in order to prevent the moisture absorbent from dropping to an organic layer, a semi-permeable membrane is attached to a rear surface of the protective cap to allow passage of moisture and oxygen.
The above-described packaging method using a protective cap made of metal or glass to protect an organic layer of an organic light emitting device from oxygen or moisture requires use of an additional material, such as adhesive or moisture absorbent, which may increase the material cost. Further, formation of a protective cap may increase the volume and thickness of the organic light emitting display and makes it difficult to apply flexibility to the display since the protective cap is made of glass.
In order to address these problems, a method of encapsulation by forming a thin bather layer is tried as another method for packaging an organic light emitting display. In this method, a film formed by laminating a plurality of inorganic insulating films and organic insulating films in multiple layers is used as the barrier layer. The reason why the barrier layer is formed by a plurality of films is to block the permeation of moisture or oxygen from the outside.
However, a barrier layer formed by stacking a plurality of inorganic insulating films and organic insulating films in multiple layers as described above has a large thickness and may generate a crack to cause damage to a substrate at the time of bending when it is applied to recent flexible display devices, which results in a bad product.